1. Field of the Invention
The present invention relates to a dielectric ceramic composition, particularly relates to a high permittivity dielectric ceramic composition wherein a relative permittivity is high as 9000 or more, change in the relative permittivity with respect to temperature is small, and an AC breakdown voltage is high.
2. Description of the Related Art
As a high permittivity ceramic composition broadly used as a ceramic capacitor, multilayer capacitor, high frequency capacitor, high-voltage capacitor, etc., conventionally, those having a BaTiO3—CaTiO3—MgTiO3 base ceramic composition as a main component have been practically used in general.
In BaTiO3—CaTiO3—MgTiO3 base dielectrics of the related art, however, the electrostatic capacity change rate with respect to temperature becomes large, when the relative permittivity is made high as 6000 or more. Also, there is a disadvantage that the AC breakdown voltage becomes low as 2.0 to 3.0 kV/mm.
The present inventors have proposed BaTiO3—CaTiO3—MgTiO3 base dielectric ceramic compositions as disclosed in the Japanese Unexamined Patent Publications (kokai) No. 3-65558 and No. 7-267723, but the relative permittivity did not reach 9000 in neither of the inventions.